Most recreational vehicles, such as all-terrain vehicles (ATVs), snowmobiles, and personal watercraft, are powered by an internal combustion engine. The operation of the engine generally is controlled by adjusting the quantity of air and fuel the combustion chambers of the engine receive, and by controlling the timing of the ignition of the air/fuel mixture in the combustion chamber. In the case of fuel injected engines, the timing of the injection of the fuel can also be controlled.
Recreational vehicles typically have one or more throttle valves in the engine's air intake system which are mechanically connected to a driver operated throttle operator, generally by a control cable. The throttle operator, generally in the form of a lever or a twist grip on a handlebar of the vehicle, is used by the driver to open and close the throttle valves to adjust the quantity of air going to the combustion chambers of the engine. An electronic control unit (ECU) located in the vehicle then controls the engine's ignition system, and in the case of a fuel injected engine, the engine's fuel injection system, accordingly. In order to have the engine generate more power, the driver uses the throttle operator to cause the throttle valve to open further. Similarly, in order to have the engine generate less power, the driver uses the throttle operator to cause the throttle valve to close. For example, in the case of an ATV moving on a level surface, opening the throttle valve results in the ATV accelerating and closing the throttle valve results in the ATV decelerating.
Recent developments in the field of automotive electronics now allow these vehicles to be equipped with what is known as a throttle-by-wire system. In such vehicles, a throttle operator position sensor senses the position of the throttle operator, transmits this position to the ECU, and the ECU sends a signal to a throttle valve actuator, an electric actuator for example, to adjust the degree of opening of the throttle valve based on the position of the throttle operator. This way, the degree of opening of the throttle valve is also a variable, in addition to the ignition and fuel injection, that can be adjusted by the ECU.
Some throttle operator position sensors consist of a fixed portion and a pivoting portion. In some of these sensors, movement of the pivoting portion relative to the fixed portion changes the value of the current or voltage passing through the sensor. In other sensors, movement of the pivoting portion relative to the fixed portion changes the value of a magnetic field generated by magnets in the sensor. From the value of the current, the voltage, or the magnetic field, the position of the throttle operator can be determined.
In vehicles where the throttle operator is a throttle lever, the pivoting portion of the throttle operator position sensor and the throttle lever are usually connected to each other so as to pivot about the same axis. U.S. Pat. No. 6,699,085, issued Mar. 2, 2004 shows one such throttle operator position sensor assembly. Although this results in a compact arrangement, because of their coaxial arrangement, forces and moments other than those necessary to pivot the pivoting portion of the throttle operator position sensor are transmitted from the throttle lever to the throttle operator position sensor. These forces and moments can result in premature wear or failure of the throttle operator position sensor. These forces and moments can also change the position of the pivoting portion relative to the fixed portion of the throttle operator position sensor, thus resulting in less accurate readings from the throttle operator position sensor.
Some vehicles are also provided with one or more additional levers on the handlebar. On wheeled vehicles, these levers could be used to actuate the brakes and/or shift gears of a transmission. On personal watercraft, these levers could be used to control a trim of the propulsion system and/or control movement of a reverse gate. Lever position sensors like the throttle operator position sensor mentioned above may be used to sense the position of these levers. As such these sensors would suffer from the same drawbacks.
Therefore, there is a need for a lever position sensor assembly that ameliorates at least some of the inconveniences present in the prior art.